In recent years' composite materials have received wide spread usage as both structural and non-structural components. A composite material is a material that is made from two or more materials having different physical and/or chemical properties. When the different materials making up the composite material are combined, they produce a new material with characteristics that are different from the individual components making up the composite material.
The use of composite materials in automotive applications is known within the industry due to their light weight and enhanced engineering and physical properties. Conventional tubular composite shafts, such as composite drive shafts, have a core shaft structure that is made of a composite material that is then connected to a metallic end fitting at each end of the composite shaft. The problem with conventional composite drive shafts is the connection between the composite core structure of the shaft and the metallic fittings attached to each end of the shaft. It is well understood that the strength of the connection between the metallic end fittings and the composite core structure of the composite drive shaft is critical to the overall performance and durability of the composite drive shaft. Conventional composite materials known in the art are unable to fuse to the metallic end fittings to the composite core structure of the composite drive shaft with sufficient strength to transfer the rotational power from one drive-line component to another. Additionally, conventional adhesives alone lack sufficient strength to bond the composite core structure to the metallic end fittings and withstand the rotational and longitudinal loads necessary to transfer the rotational power from one component in the vehicle drive-line to another. It would therefore be advantageous to develop a composite drive shaft having a robust attachment to a metallic end fitting and/or other drive line components thereby providing improved functionality and viability.
Typically, the composite core structure of composite drive shafts known in the art are attached to the metallic end fittings by using one or more welds, pins, bolts, screws, flanges, sleeves and/or adhesives. This adds unnecessary complexity to both the manufacturing of the composite structure and the assembly of the composite drive shaft. Additionally, this adds unnecessary weight to the composite drive shaft thereby mitigating one of the main benefits for using composite materials. It would therefore be advantageous to develop a composite drive shaft that does not require the use of mechanical fasteners or mechanical connectors to attach the metallic end fittings to the composite core structure of the composite drive shaft.